摘要
通过调控酸碱浓度,在水热条件下得到了金红石、锐钛矿、板钛矿、钛酸钠等一系列TiO2/钛酸盐产物.对上述TiO2、酸洗处理后的钛酸盐等一系列不同晶型、不同形貌的样品进行焙烧处理,系统性地研究焙烧温度的逐渐升高对产物晶型转变和形貌演化的规律性影响.给出了水热酸碱浓度以及焙烧温度两个因素与TiO2/钛酸盐纳米材料晶型和形貌变化行为关系的二维示意图.依据奥斯特瓦尔德阶梯规则、经典热力学理论以及定向附着生长机理,对TiO2/钛酸产物的晶型晶体生长、晶型转变和形貌演化机理进行了探讨.
Titania/titanate nanomaterials including rutile, anatase, brookite TiO2 and sodium dititanate and trititanate were obtained by regulating the acid/alkali concentration under hydrothermal treatment. A systematical investigation was estab- lished to uncover the phase transition and morphological evolution behaviors of TiO2/titanate nanomaterials by calcining the samples including rutile TiO2 nanorods, anatase TiO2 nanocrystallines, brookite TiO2 nanoflowers, acid washed dititanate H2Ti205 nanosheets and trititanate H2Ti307 nanowires at 400, 600, 800 or 1000 ~C for 4 h in air with the heating rate of 2 ~C/min. After heat-treatment, the products were taken out from the oven and cooled down to the room temperature. Rietveld refinements of the powder X-ray diffraction （XRD） pattern were used to generally assess the phase composition of the dif- ferent samples and their crystallite sizes, and to further investigate the phase transition behavior in company with the syn- thetic parameters. FESEM, TEM, and HRTEM were used to characterize the morphology evolution and to further elucidate the morphological evolution of the resulting products. The crystalline phase distributed diagram of TiOE/titanate nanostruc- tures dominated by the two experimental parameters indcluding acid/alkali concentration and calcination temperature was presented in the current work based on our experimental results, in which revealed the 5 types of phase transition and mor- phological evolution behaviors of titania/titanate nanomaterials. 1. Rutile nanorods→rutile nanorod aggregations → rutile micro particles. 2. Anatase nanocrystallines → anatase nanoparticle aggregations → rutile micro particles. 3. Brookite nano- flowers →brookite nanoflower clusters →rutile micro clusters. 4. Dititanate H2Ti205 nanosheets -＋anatase nanoparticle aggregations → rutile micro clusters. 5. Trititanate H2Ti307 nanowires →TiO2-B nanowires → anatase nanowire aggrega- tions → rutile micro clusters. The crystal growth and phase transition mechan
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2013年第1期93-101,共9页
Acta Chimica Sinica
基金
上海市国际科技合作基金(No.11520706100)
上海市青年科技启明星计划(B类)(No.12QB1402800)
国家自然科学基金(No.21071098)
国家国际科技合作项目(No.2011DFA50530)资助~~
关键词
二氧化钛
钛酸盐
焙烧处理
晶型转变
形貌演化
机理
wtitania
titanate
calcinations
phase transition
morphological evolution
mechanism
